1. Field of the Invention
The present invention relates to a dispensing device intended to equip a container, especially a container containing a cosmetic product, comprising a base part and a mobile assembly which can move with respect to this base part and defines therewith a variable-volume pumping chamber.
2. Description of Related Art
European Patent Application EP-A-0 011 487 discloses a device of this type, in which the mobile assembly comprises a piston mobile between two extreme positions and a control member, this control member being secured to the piston and passing through the base part and being equipped with an outlet passage allowing the product contained in the pumping chamber to be dispensed, the piston comprising at least one intake passage allowing the pumping chamber to be filled, the control member being mobile with respect to the piston between a dispensing position and a filling position, the piston comprising shut-off means for shutting off the outlet passage, these shut-off means being suitable for shutting off this passage when the control member is in its filling position and/or the control member comprising shut-off means for shutting off the intake passage, these shut-off means being suitable for shutting off this passage when the control member is in its dispensing position, the control member comprising a first drive means designed so as to collaborate with the piston when the control member is in its dispensing position, so as to drive it along in a direction corresponding to a reduction in the volume of the pumping chamber, the control member comprising a second drive means designed so as to collaborate with the piston when the control member is in its filling position, so as to drive it along in a direction corresponding to an increase in the volume of the pumping chamber.
In this known device, the piston slides with a high friction with respect to the base part, which tends to lead to a rapid wear and makes the manipulation of the device relatively difficult.
The invention aims to further enhance a device of the aforementioned type.
It succeeds by virtue of the fact that the base part is designed so as to create a friction between the piston and the base part when the volume of the pumping chamber is minimum, and an absence of friction or smaller friction when the piston is in an intermediate position between its extreme positions.
By virtue of the invention, the friction is sufficient between the piston and the base part at the end of the dispensing of a product dose so that the control member is able to move with respect to the piston and reach the filling position.
In addition, the piston may move without friction on the base part or with a smaller friction during the filling of the pumping chamber, which decreases the wear of the components and facilitates the manipulation of the control member.
In one preferred embodiment of the invention, the base part is designed so as to create a friction between the piston and the base part when the volume of the pumping chamber is maximum and an absence of friction between the piston and the base part when the piston is in an intermediate position between its extreme positions.
In one preferred embodiment, the base part comprises at least a first portion with an inside diameter smaller than or equal to the outside diameter of the piston and a second portion with a diameter greater than the diameter of the piston, the first portion contacting the piston when the volume of the pumping chamber is minimum.
In one particular embodiment, the base part comprises a third portion with a diameter smaller than or equal to the diameter of the piston, and contacting the piston when the volume of the pumping chamber is maximum.
Again in one particular embodiment, the axial dimension of the first and third portions of the base part is smaller than or equal to twice the axial dimension of the piston.
Thus, the major part of the displacement of the piston may be achieved without friction with the base part.
The dispensing device of the invention has a low number of elements, is inexpensive to manufacture, and operates reliably.
Advantageously, the piston comprises shut-off means for shutting off the outlet passage, these shut-off means being suitable for shutting off this passage when the control member is in its filling position, and the control member comprises shut off means for shutting off the intake passage, these shut-off means being suitable for shutting off this passage when the control member is in its dispensing position.
As a variant, the piston comprises shut off means for shutting off the outlet passage, these shut-off means being suitable for shutting off this passage when the control member is in its filling position, and shut-off means for shutting off the intake passage.
As another variant, the control member comprises shut-off means for shutting off the intake passage, these shut-off means being suitable for shutting off this passage when the control member is in its dispensing position, and shut-off means for shutting off the outlet passage.
In one particular embodiment, the shut-off means for shutting off the intake passage act as the first drive means.
In one particular embodiment, the piston consists of a disc provided with a central aperture for the passage of the control member and with filling orifices distributed around this central aperture, these orifices constituting the intake passage.
In one particular embodiment, the control member comprises a control rod extending, at one end, out of the base part and equipped, at this end, with an element for grasping and with a product outlet orifice.
In one particular embodiment, the control rod comprises, at its opposite end, having passed through the piston, a plate suitable for shutting off the intake passage in the piston when the control member is in its dispensing position.
In one particular embodiment, the plate has openings encouraging product to flow towards the intake passage in the piston.
In one particular embodiment, the second drive means consists of a stop formed on the control rod.
In one particular embodiment, the outlet passage opens via a radial orifice onto the control rod between the first and second drive means and the shut-off means for shutting off the outlet passage consists of a cylindrical surface of the central aperture of the piston, said cylindrical surface having a height shorter than the distance separating said radial orifice and the first drive means and a height greater than the distance separating said radial orifice and the second drive means.
In one particular embodiment, the base part is shaped to increase the friction of the piston on the base part when the volume of the pumping chamber is minimum or maximum.
In one particular embodiment, the base part is designed so as to be fixed onto the neck of the container.
Another subject of the invention is a container equipped with a dispensing device as defined hereinabove.
A further subject of the invention is the use of a container such as the aforementioned, head down.